Yamaha p5000s Service Manual page 40

P5000S / P7000S
6.4 Repair concrete instance at the trouble part
All secondary output isn't output.
Check the following instruction.
① Confirm the resistor value of R416, R451(6.8Ω 5 W).
Exchange if open the resistor value.
② Confirm the resistor value of Q406, Q407 Between C-E.
If short or several value(Ω), remove the part and then exchange IC402 because it is broken.
③ Conform the resistor value of R420, R421.
Confirm whether or not it is a 10Ω.
Remove if open or a resistor value is increased.
④ Conform the resistor value of R419.
Confirm whether or not it is a 4.7Ω.
Remove if open or a resistor value is increased.
⑤ Conform the resistor value of R429, R430.
Remove if open or a resistor value is increased.
⑥ Confirmation of F401.
Confirm the resistor value of F401.
Don't install the test of ⑦ ends.
⑦ Conform a waveform of IC402.
Confirm alternating volts.
【Note】
The earth of the measuring machine doesn't connect.
The parts sometimes damages when using in the connecting condition.
After ① - ⑦ ending, it observes a waveform IC402-1Pin(Lo),2Pin(COM) with the oscilloscope.
There is good if being the square wave (0-15V) of the about 70 kHz.
In the waveform malfunction case, confirm that the output of IC403 (regulator) is +15 V.
In case of equal to or less than 15V, it exchanges IC402 and it observes a waveform once again.
(When exchanging IC402 already by ② , you exchange IC401).
* When observing a waveform, do short-circuiting of PR401.
⑧ Exchange the parts which was removed by ① - ⑦ for the normal part.
⑨ It is repair completion if confirming "6-2. Electric performance" and not being in the problem.
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